1. Field of the Invention
The present invention relates to a zoom lens, and an image pickup apparatus using the same. The present invention, in particular, relates to a zoom lens and an image pickup apparatus which are suitable for a compact digital camera.
2. Description of the Related Art
In recent years, digital cameras in which, an arrangement is made to photograph an object by using a solid image pickup element such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor) have become mainstream, replacing a silver-salt film camera. Furthermore, such digital cameras have a wide range of categories from a high-function type for professional use to a compact popular type.
A user of such digital camera of the popular type seeks to enjoy photography by capturing readily a wide variety of scenes anytime and anywhere.
Therefore, a small-size product, particularly a slim digital camera, which can be accommodated easily in a pocket of clothes or a bag and carried conveniently, has been preferred. Moreover, further small-sizing of a taking lens system has been sought.
Furthermore, in order that capturing can be carried out also with high intensity, a digital camera which carries out image processing such as widening a sensitivity area of dynamic range has also been proposed. Accordingly, photography in which capture conditions are not restricted has become possible.
Even in such photography including photography at dark places, electronic correction of intensity is possible to a certain extent. Here, by adopting a lens having a large lens aperture, it is possible to deal with photography even at darker places. As a result, it is possible to widen conditions under which the photography is possible.
Furthermore, in the lens having a large aperture, photography with clarity is possible even with a small amount of incident light. Therefore, it is possible to increase a shutter speed in continuous capturing of a moving object, to further higher speed. In such manner, many options are made available to a photographer. Therefore, in recent years, a lens having a large lens aperture has been drawing attention.
Furthermore, from a point of view of widening of a capture area, the demand for high magnification zoom is still there. Therefore, further higher magnification has been anticipated.
As a prior art in which, a zoom lens having a small F-number with a comparatively higher zoom ratio, a technology in which, the zoom lens includes in order from an object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a positive refractive power, has been proposed (Japanese Patent Application Laid-open Publication No. 2010-217478).